©Fraunhofer ISE/Foto: Guido Kirsch
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MODULE DESIGN, YIELD AND LCOE
How larger solar cells impact power, efficiency and performance
Max Mittag, Andrea Pfreundt, Jibran Shahid, Sebastian Nold, Andreas Beinert
Fraunhofer Institute for Solar Energy Systems ISE
Webinar PV-magazine
Freiburg, 23.04.2020
www.ise.fraunhofer.de
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Larger Cells Motivation & Problems
More power output per cell, Same amount of handling steps
Reduced costs in cell production
Higher cell power higher module power
Larger cell = higher currents = higher electrical losses
Larger cell = changed area/circumference-ratio = reduced internal reflection gains
Larger cell = larger module
mechanical stress, logistics, equipment reconfiguration,…
Advantages
Challenges
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Cell-to-Module (CTM) Ratio Introduction
Module power cell power
Module efficiency cell efficiency Cell-to-Module power losses = financial losses
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Cell-to-Module (CTM) Ratio CTMefficiency and CTMpower
Large power gains, low efficiency High efficiency, small power gains
solar cell solar cell
CTMpower
CTMefficiency
CTMpower
CTMefficiency
Cells are bought at €/Wp; Modules are sold at €/Wp
Increase of CTMpower = economic advantage for module manufacturers
Where is the benefit of larger cells for modules ?
𝐶𝑇𝑀𝑃𝑜𝑤𝑒𝑟 =𝑃𝑚𝑜𝑑𝑢𝑙𝑒
𝑃𝑐𝑒𝑙𝑙𝑠
𝐶𝑇𝑀𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑦 =𝜂𝑚𝑜𝑑𝑢𝑙𝑒
𝜂 𝑐𝑒𝑙𝑙𝑠
?
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Larger cells: Impact on Modules Roadmap to Trina Vertex
Analysis performed using SmartCalc.CTM
Bottom-up analysis of module designs
Easily access ible via graphical user interface
Round wire, shingling, bifaciality, non-STC performance, cell size & metallization, material variation,…
Reduction in development costs & strategic concept analys is
Half Cell
M2
Larger Cells
M4, M6, M12
Third Cells
M12
Optimization
Vertex
SmartCalc.CTM www.cell-to-module.com
free demo version
Why did Trina designed the Vertex module the way they did?
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Larger cells: Impact on Modules Roadmap to Trina Vertex
Larger cells lead to higher module power and efficiency
CTMpower decreases
CTMefficiency increases
cell format 156.75 158.75 161 166 210
half cell
Cell / string spacing normal
Module design 6x24
Module power [Wp] 406 417 429 456 725
CTMpower 102.3% 102.3% 102.3% 102.1% 101.0%
module efficiency [%] 20.2 20.2 20.2 20.3 20.7
CTMefficiency 89.0% 89.2% 89.3% 89.6% 91.4%
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Larger cells: Impact on Modules Roadmap to Trina Vertex
Problematic module dimensions with larger cells
Solution: fewer strings and shorter strings
cell format 156.75 158.75 161 166 210
half cell
Cell / string spacing normal
Module design 6x24
Module power [Wp] 406 417 429 456 725
CTMpower 102.3% 102.3% 102.3% 102.1% 101.0%
module efficiency [%] 20.2 20.2 20.2 20.3 20.7
CTMefficiency 89.0% 89.2% 89.3% 89.6% 91.4%
Module length [m] 2.02 2.04 2.07 2.13 2.65
Module width [m] 1.00 1.01 1.03 1.06 1.32
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Larger cells: Impact on Modules Roadmap to Trina Vertex
cell format 156.75 158.75 161 166 210
half cell third cell
Cell / string spacing normal
Module design 6x24 5x20 5x30
Module power [Wp] 406 417 429 456 725 504 511
CTMpower 102.3% 102.3% 102.3% 102.1% 101.0% 101.6% 103.0%
module efficiency [%] 20.2 20.2 20.2 20.3 20.7 20.5 20.5
CTMefficiency 89.0% 89.2% 89.3% 89.6% 91.4% 90.5% 90.6%
Module length [m] 2.02 2.04 2.07 2.13 2.65 2.22 2.25
Module width [m] 1.00 1.01 1.03 1.06 1.32 1.11 1.11
Why not just build a half cell module?
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Larger cells: Impact on Modules Roadmap to Trina Vertex
Increas ing electrical losses for larger cells
Solution: third cut cells
cell format 156.75 158.75 161 166 210
half cell third cell
Cell / string spacing normal
Module design 6x24 5x20 5x30
Module power [Wp] 406 417 429 456 725 504 511
CTMpower 102.3% 102.3% 102.3% 102.1% 101.0% 101.6% 103.0%
module efficiency [%] 20.2 20.2 20.2 20.3 20.7 20.5 20.5
CTMefficiency 89.0% 89.2% 89.3% 89.6% 91.4% 90.5% 90.6%
Module length [m] 2.02 2.04 2.07 2.13 2.65 2.22 2.25
Module width [m] 1.00 1.01 1.03 1.06 1.32 1.11 1.11
Interconnector losses k12, rel 0.5% 0.5% 0.6% 0.6% 1.3% 1.3% 0.6%
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Larger cells: Impact on Modules Roadmap to Trina Vertex
Trina Vertex
Smaller spacings decrease power but increase efficiency
cell format 156.75 158.75 161 166 210
half cell third cell
Cell / string spacing normal small
Module design 6x24 6x20 5x30 5x30
Module power [Wp] 406 417 429 456 725 504 511 505
CTMpower 102.3% 102.3% 102.3% 102.1% 101.0% 101.6% 103.0% 101.7%
module efficiency [%] 20.2 20.2 20.2 20.3 20.7 20.5 20.5 21.1
CTMefficiency 89.0% 89.2% 89.3% 89.6% 91.4% 90.5% 90.6% 93.2%
Module length [m] 2.02 2.04 2.07 2.13 2.65 2.22 2.25 2.18
Module width [m] 1.00 1.01 1.03 1.06 1.32 1.11 1.11 1.10
Interconnector losses k12, rel 0.5% 0.5% 0.6% 0.6% 1.3% 1.3% 0.6% 0.5%
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Cell-to-System (CTS) Analysis
Laboratory conditions (STC) real world (non-STC)
Half cells with lower electrical losses in systems
PERC with lower module temperature than AlBSF
HJT with better temperature coefficients
…
Different module designs have different outdoor performance
Cell-to-System bottom-up multi-physics analysis of loss channels in PV modules at realistic non-STC conditions for flexible module designs
Optical Model
Thermal Model
Electrical Model
Module Power / Yield
Material Properties & Module Design
Envi
ron
men
t &
Op
erat
ion
SmartCalc.CTM www.cell-to-module.com
free demo version
Loss channel analysis at Fraunhofer ISE
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CTS-Analysis Vertex Non-STC Performance
Higher power density (Wp/m²) for Vertex than for half cell module
Slightly higher temperature for Vertex
(higher active area share higher absorption higher temperature)
Electrical losses of half cell relatively lower at low irradiance (Ploss = I² x R)
Opposing effects
Power density advantage of Vertex compared to half cell reference
𝜂𝑟𝑒𝑙 = 1 − 𝑇𝑚𝑜𝑑 − 25°𝐶 ∙ 𝛾𝑃𝑀𝑃𝑃 ∙𝑃𝐸
𝑃1000 𝑊/𝑚²∙1000𝑊/𝑚²
𝐸
Normalizes temperature effects Normalizes irradiance effects
Mittag, M. et al, „Techno-Economic Analysis of Half-Cell Modules”, EU PVSEC 2019 Mittag, M. et al, „Thermal Modelling of PV Modules and Processes“, EU PVSEC 2019
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LCoE-Estimation
Cost estimation based on a lot of sensitive data
Simple approach chosen here
52% of module costs are solar cells
Modules with higher active area share have higher production costs
Vertex module has higher absolute module costs (€)
Vertex has higher power density
Differences in module performance
Not all system costs depend on area
LCoE estimation
Cost structure of half cell module manufacturing
ITRPV 2019
Cost analysis based on exemplary manufacturing using a simple model Costs are not prices (no margins included, no logistics, etc.)
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LCoE-Estimation
Module manufacturing costs estimated
DC yield calculation performed with SmartCalc.CTM
System costs estimated
80% system efficiency (lowers module yield)
Inverter & Cabling increase with module wattage
Ground & Mounting increase with module area
LCoE estimation based on simple approach
ITRPV 2019 144 half Vertex 144 half Vertex per module per Watt
Inverter 100% 124% 100% Wiring 100% 124% 100% Mounting 100% 119% 100% 96% Ground 100% 105% 100% 84%
System Costs 144 half Vertex [€/module] 100% 117%
[€/m²] 100% 99% [€/kWp] 100% 95%
[€ct/kWh] 100% 95%
Yield calculation for Breisach, Germany
144 half Vertex 100% 122%
144 half Vertex 100% 124%
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Thank you for your Attention!
Fraunhofer Institute for Solar Energy Systems ISE
Max Mittag
www.ise.fraunhofer.de
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Holistic Module Development Mechanical Stress
Power, Costs, Reliability, Integration…
Module Development becomes increasingly difficult due to many new approaches
Example: Mechanical Stress
Larger modules
Increased mechanical stress
Larger cells
Increased mechanical stress
Cut cells
Reduced stress
Complex evaluation of new designs
Half cell module Third cell module
Mechanical load simulation (5400 Pa push load)
Beinert, A. et al, „Thermomechanical evaluation of new PV module designs by FEM simulations”, EU PVSEC 2019
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Module Comparison
Reference Module
392 Wp
19.8% module efficiency
CTMpower = 98.0%
CTMefficiency = 87.4%
Trina Vertex
505 Wp
21.1% module efficiency
CTMpower = 101.7%
CTMefficiency = 93.2%
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Module Comparison
Reference Module
6x24 (144) cells
156.75 x 78.375 mm² (fsq)
2.02 x 1.00 m² module area
Glass, white backsheet
10 round wire interconnectors
22.65% (2.76 Wp) *
Trina Vertex
2x 5x15 (150) cells
210 x 70 mm² (fsq) third cut cells
2.18 x 1.10 m² module area **
Glass, white backsheet
10 round wire interconnectors
22.65% (3.31 Wp) *
* Assumed for analysis ** Datasheet Trina Vertex
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